The end of the 1950s brought a lot of innovation to Hamilton's watch line up. Electric models were newly introduced. Watches were getting "thin". Lots of models used a variety of automatic movements. Many models were marketed as "weatherproof".
Hamilton's first foray into environmentally protected watches was their "CLD" line... or "sealed". Prior to that most models were dust-proof, if that.
There are three cardinal rules to vintage watches... (1) don't drop them, (2) keep them away from magnets, and (3) don't get them wet. Once water gets inside the case it can wreak havoc with the dial, hands, and the movement.
To be waterproof there are special tests that need to be performed. A watch may be waterproof initially but after a few years of normal use, gaskets can leak, etc and you'd be wise to treat a nice waterproof watch like any other watch - and keep it away from the water. Save the swimming, showering, car washing for a watch you consider disposable.
The typical approach to waterproofing a case is to limit the number of ways water can get in. Having a one-piece case that opens through the crystal helps a lot. Having a round crystal that is press-fit into the case offers a great seal. That leaves just the stem opening and a crown with a gasket offers a good seal - for a while. Most water-damaged watches I have seen have moisture getting in through the stem tube.
The 1959 Sea-Cap was marketed as "waterproof" but I wouldn't trust one today. It's actually an unusual design and different from most waterproof watches. It has a two piece with a gasket in between.
The Sea Cap was produced for three years. The first year offered a metal bracelet with a leather insert. You had your choice of a white-dialed or a black-dialed model with luminous hands and markers.
The later two years displayed a different bracelet design - so if you have an original bracelet you might be able to date the watch.
Tucked inside the Sea Cap you will find a Hamilton 671 movement. This Swiss-made movement is based on the ETA 1080 and it's very similar to the 672 Automatic movement, the latter having the extra bits of the automatic framework attached to the back.
My project watch is a black dialed version. I has a metal/leather bracelet that looks great with the watch but isn't quite the original design. There's something amiss with the crown - it shouldn't be sticking out so far - it's a bit wobbly.
You can see the pronounced lip on the case back between the lugs where you can insert a case knife to pry the back off. Notice there's a stem tube... it's part of the case back, not the front. So this will require a two piece stem.
The owner of the watch sent along a white dialed Sea Cap to use has a donor if necessary. It doesn't have a crown but if the black version goes well, maybe I can rescue them both.
With the front of the case out of the way, you can see the movement and dial are retained in the case back. There's a black gasket surrounding the circumference. The crown unscrewed off so I should be able to lift the movement out of the case back with the stem intact.
The 671 movement appears to be in good shape. The female side of the two-piece stem isn't rusty at all - that's a great sign.
The male-side of the stem (called a hub) is dirty at best, and hopefully not rusted. With luck I'll be able to reuse the stem and crown.
Everything is disassembled and cleaned. It's now all bright and shiny.
The balance wheel has tiny weights around the perimeter. These weights are used to poise, or balance, the wheel but also serve to adjust the timing. One of the weights came off in the ultrasonic cleaner. You can see it in the photo below. Can you tell where it's supposed to go?
Without that tiny weight, the balance would run a LOT faster and the timing would vary based on position (dial up, dial down, etc). I need to put it back in the correct spot. Each side of the wheel is symmetrical so I just need to find the spot where there's a weight on one side but on 180 degrees opposite. In order to install such a tiny screw, you really need a pin vice, like shown, to grasp the screw so you can insert and turn it in the proper spot.
The reassembled movement is now ticking away with a good motion. The amplitude is a little low but that's because the movement isn't fully wound yet. A quick tweak to the regulator will slow it down a smidgen.
The finished watch looks great. Black dials are extremely hard to photograph as they show every spec of dust that could land on the crystal.
Since nothing needed to be replaced on the black Sea Cap, I was able to restore the white Sea Cap too. It just needed a male stem hub and a new crown
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